The HOTT Archive

Summary

This is an online archive of maps of dust optical depth (τ) at 1 THz and dust temperature (T) in Galactic molecular clouds from Singh & Martin (2022), with an initial focus on the Gould Belt survey regions. These parameter maps were generated by fitting a modified blackbody spectral energy distribution (MBB SED) to submillimetre data from the Herschel Space Observatory. The original intensity maps are publically available in the Herschel Science Archive. The Herschel data used were taken in parallel mode at 250, 350 and 500 µm using the SPIRE instrument and at 160 µm using the PACS instrument, brought to a common resolution of 36.4″ FWHM and pixel size of 14″, the values of the native 500 µm map.

The Planck thermal dust model (Planck Collaboration et. al. 2014) at resolution 5' was used to find the zero level adjustments for the Herschel maps and for a contextual background for mosaics in which the HOTT parameter maps could be embedded. The spectral index (power law exponent β) of the dust opacity for the MBB model was interpolated from the Planck product at 30' resolution.

A comprehensive analysis of uncertainties in the Herschel data provides the basis for an SED fit of the MBB parameters τ and T, using the χ² metric. The full pipeline with detailed error analysis is described in Singh & Martin (2022). Analysis of residuals from the SED fits across many fields supports the overall appropriateness of the assumed MBB model and points to where it breaks down. Finding χ² distributions close to the theoretical expectation boosts confidence in the pipeline and the optimized quality of the parameter maps and their estimated uncertainties.

Mosaics of HOTT τ maps embedded for context in lower resolution τ from the Planck thermal dust model provide a contextual overview of all of the regions.

Navigation tips are provided for downloading the HOTT parameter maps for individual fields, and previewing or downloading plots relating to zero-level adjustments and the analysis of residuals and χ² of the SED fits.

A bibliography is provided. Any use of these data should cite the HOTT paper by Singh & Martin (2022).

See also Additional information.

There are two ways to select a region. (i) Click the Regions navigation button on the home page and select a region from the list on the left. (ii) Click on the region name in the list of Mosaics on the left of the Home page, and then again on the region name or the selected τ mosaic. Both ways lead to a preview of τ and T mosaics of the region.

Each region can have several HOTT fields as annotated on the τ mosaic. Click on the link to an individual field to pop a data window.

For each field, there are in total seven maps in FITS format from the analysis (see right side panel). They are bundled in a zip file. Left click to download this file.

There are also several plots in PNG format from the analysis (see right side panel). For the individual PNG plots, left click to preview or right click to download.

1. Optical depth (τ) at 1 THz
2. Error of τ at 1 THz
3. Dust temperature (T) [K]
4. Error of T [K]
5. β from the Planck thermal dust model
6. Radiance [W m^-2 sr^-1]
7. χ²

1. Zero-level adjustment at each of four passbands
2. Analysis of residuals and χ² of the SED fits

The paper decribing the full pipeline and error analysis is Singh & Martin (2022).

Some papers using HOTT parameter maps can be found in this NASA ADS Library.